A VIRAL infection five years ago left Maureen Betts with pain in her joints and back so severe that she was unable to work and needed crutches or a wheelchair to get around. Morphine made the day more bearable, but life was far from pleasant.

Then three months ago she was introduced to microcurrent therapy. A battery-operated gadget the size of a Walkman delivers very low voltage, low-frequency electric currents that not only ease pain but are believed to stimulate the healing process. The current is delivered directly to the painful area via two electrodes attached to the skin.

Ms Betts, who lives in Norfolk, has been able to reduce her morphine dosage by 25 per cent. 'It's not a cure, but the pain is less and my quality of life is better,' she says. 'Walking is easier, I have more dexterity in my hands and I don't need to spend so much time sleeping or resting.'

In the United States, microcurrent machines have been used in the treatment of skin ulcers, fractures, severe cancer pain, inflammation and back pain. Fifty such units (brand name Ultima) are now being distributed in the UK by a British medical equipment company, though they are not yet available generally on the National Health Service.

At first glance, the microcurrent machines appear no different from those used to deliver transcutaneous electrical nerve stimulation (Tens), which also involves applying an electrical current through electrodes attached to the skin. But the current used in the new treatment is a thousand times weaker than that used in Tens, and it has a different physiological effect.

Whereas Tens blocks pain by acting on the nerve bundles travelling from the pain area, the new therapy is believed to work directly on the damaged or inflamed cells, altering the electrical activity in the injured area and triggering chemical reactions involved in the healing process. Unlike Tens, microcurrent therapy is also thought to have a long-term effect: each time it is used, the treatment time needed gets shorter and the pain relief obtained lasts longer. The patient rarely feels any sensation while the electric current is being applied.

Microcurrent machines have only recently attracted the interest of British consultants. One anaesthetist (who wishes to remain anonymous) from an NHS pain clinic in the North of England, will be carrying out the first clinical trial in the UK.

In addition, at Dundee Royal Infirmary's pain clinic, two microcurrent therapy machines have been in use for the last three months. Anne Kelly, a ward sister in the clinic, says that the treatment 'certainly seems promising'.

Microcurrent therapy is based on the theory that electrical circuits operating within the body play an important role in healing. Robert Charman, senior teacher at the Cardiff School of Physiotherapy, says: 'We are familiar with the effects of electricity on the 'excitable' cells such as muscles and nerves, which use it to convey messages. But we are now looking at the electrical properties of other cells and tissues in their own right.'

Carefully applied electrical frequencies, he says, can actually induce bioelectrical changes in cell activity.

Studies published in the American Journal of Surgery and Physical Therapy have shown that microcurrent therapy accelerates healing in skin ulcers and suppresses bacterial growth. In another study, also published in Physical Therapy, a physiotherapist for the Canadian Olympic team who used microcurrent therapy on athletes with ligament and tendon injuries found that recovery time was reduced by two-thirds.

The microcurrent machine is not the only electrotherapeutic device. The Liss Cranial Stimulator applies high-frequency stimulation to the head and is used in patients suffering from insomnia, migraine and depression.

David Dowson, of the Centre for the Study of Complementary Medicine in Southampton, believes that the stimulation acts on the brain's chemical messengers, thought to be abnormal in those with depression and insomnia. 'With migraine, there is an alteration in the brain's circulation and I believe this can be reversed by electrical stimulation,' he says.

A study of whether the Liss stimulator was effective in preventing migraine was recently carried out at the City of London Migraine Clinic, a medical charity linked to St Bartholomew's Hospital. Anne MacGregor, who carried out the research, says that for some sufferers the device had 'some effect' but feels that more research is needed.

Another device developed to treat migraine, the Novagen, is based on the theory that in migraine sufferers the brain's electrical output at certain frequencies is lower than normal.

With the help of a computer, the patient's electroencephalogram, a recording of the brain's fluctuating electrical activity, is analysed and the Novagen, a battery-operated pulsed magnetic field generator, is programmed to artificially 'fill in' the gaps in the brain frequencies. The signal is passed to the brain when this small device is worn close to the skin, for instance on a cord around the neck.

Until these devices have been subject to scientific trials, no one can be sure how effective they are. Dr MacGregor says: 'There is a very effective placebo response in migraine - up to 60 per cent of sufferers will respond to a placebo treatment.

'Several of our patients who have tried the Novagen have said it is effective, but unless you do a proper clinical study you can't say it is a cure for migraine.'

Microcurrent therapy: Spembly Medical Ltd, Newbury Road, Andover, Hampshire, SP10 4DR.

The Liss Cranial Stimulator: send an sae to Dr David Dowson, Centre for the Study of Complementary Medicine, 51 Bedford Place, Southampton, Hampshire SO1 2DG.